Can't Heat 4th Floor Apartments in Front

nicholas bonham-carter

what is the pressure of your system?

i think you need a lot  more venting of the mains. also, you need a good low-pressure  gauge, as i mentioned several weeks ago.

remember that the main vents are only controlling the escape of air in the system, and that with them you can only control the steam arrival at the risers. if the mains are massively vented, then my view is that the arrival of steam at all the risers is almost instantaneous, [at 88 FPS]. i would put the same several gorton #2's on each return. you can never have too many vents!

find out how to jumper the starting control for the boiler, so that you can make some tests without running upstairs, to enter some settings into the heat-timer. find out if steam is arriving simultaneously, based on the radiator temperature.

you might want to use a good thermostat, instead of the heat-timer, for a while to get the system sorted out, and see if the heat-timer might be part of the problem.--nbc

Steamhead

OK, the first part is shared

You might be able to get away with adding just one Gorton #2 to each 70-foot run, leaving the existing Gortons and the Hoffman #75 vents in place.



As to the pressure, jpf is right. A steam system always starts at zero pressure, so you need to vent at as low a pressure as possible.

Jeremy_16

After reading all of the comments,

it sounds like it may be best to buy 2 additional Gorton #2s for each long main so I end up with a total of 4 Gorton #2's on each long main to the front of the building (or at the very least buy 1 additional Gorton #2 for each long main to the front). That way I will have the maximum amount of venting on the menorahs set up in the front.



My plan would be to re-use the Hoffman #75's on the shorter back of the building mains that currently have no main vents. Does this sound like a good idea, or would adding more venting in the back take away from the front? It would be much easier if I could just go in and out of apartments anytime I wanted, but since there are tenants in each unit, it's not so easy to test out ideas, time the steam, and try different set-ups, etc.



The back of building, despite having no main vents, seems to heat fine... Occasionally the top floors will be a bit cooler than the lower floors, but steam doesn't seem to have a problem reaching any of the back apartments no matter what floor.



Thanks for all of the advice and information.

jpf321

maximize and measure

maximize the venting to as close to open pipe as possible .. aren't you in NYC? i'd love to stop by and poke around .. contact me directly .. perhaps I can also loan you my temp dataloggers for some measuring tests ..



anyway .. maximize all venting as much as possible to take the timing for steam arrival to vent point out of the equation ..



assuming they are in good working order, the hoffmans on the back would be fine .. i think that it was in this thread that steamhead taught me not to de-vent/limit  an area but rather to increase venting on the weak area. how's your pipe insulation? i've gotten to know the guys at Allstate Insulation in Maspeth ... they are very helpful.

Jeremy_16

JPF

I'm actually located in Boston, but if you ever are in my neck of the woods, let me know.



I did run the open pipe test with 3/4 inch pipe and it reduced the time it takes steam to arrive at the end of the main by a few minutes compared to when I just had one Hoffman #75. Like I said before though, it's hard to run tests because I have to go in and out of tenants' apartments multiple times. They've been nice about it so far, but I don't want to push my luck. It's also tough because to test accurately it is usually best to do it from a cold start, no? Then I have to turn the boiler off for a few hours. If I do it from a warm start then it will naturally not take as long for steam to reach the end of the main because the pipes are already warm.



We purchased some 1 inch thick fiberglass insulation for areas where the mains are not buried in the walls, but haven't put it on any pipes yet. The header isn't insulated, so I figure that should help once covered. I wanted to see how much the Gorton #2's helped first before adding insulation.



The two 70 foot long mains that go to the front of the building are not insulated the whole way. The parts that I can see when I poke my head inside the wall are not covered. No one on the board seemed to indicate that it would be worth it to open up the walls just to insulate the pipes inside. Either way, It would be pretty disruptive to the tenants. Unless it would make a pretty big difference, I'll just leave the pipes in the wall alone. After adding a couple more Gorton #2's I'll start on the insulation in accessible areas and let you know how it helps.

jpf321

cold start vs. warm start ...

i would do my testing using the more common start .. all my testing is done with my boiler water at lest 170dFahr since I have an aquastat on there for my DHW and I will never be below there.



yes things will certainly change depending on temp of boiler and pipes .. but you can never really get the same start conditions every time.



as I mentioned here the other day, warm pipes will increase speed to main end. if your system will likely never be off for longer than X time, don't test with it being off for longer.

nicholas bonham-carter

open pipe test

when you do that test again, can you hear any noises indicating a sag of water-filled pie restricting the flow- something like panting or gurgling?

don't forget how important low pressure [8 ounces is ideal] is in the speed of steam arrival!---nbc

FJL

Cut In ...

With an 8 oz cut out, what would you recommend for the cut in?  I'm currently operating my apt building (4 story/4 units) at 12oz/4oz.

Jeremy_16

Pressure is set to cut in at .5 PSI and out at 1.5 PSI

When I did the open pipe test a few weeks ago I listened for sounds. About a minute or two before the end of the main got hot I heard water rushing through, but I think it was from the condensing process. There was no banging or water hammer sounds. It did sound like the air would come out in spurts at first. A rush of air and then nothing, then a more air, until eventually the air was coming out more constantly. Does that sound right?



When I did the open pipe test in the back of the building, it seemed like the steam rushed out faster with less spurts of air then no air, but I last tested that out several weeks ago, so I might not be remembering exactly right, but that was my general impression. I also heard the water sounds in the back but I think it was just condensate flowing towards the wet return like in the front of the building.



Last time I listened to the main vents (from the front of the building), they began venting air about 5 minutes after I started the boiler. With one Hoffman #75 it took about 14.5 to 15 minutes for the end of the main to get warm (from the start of turning the boiler on from a cold start). With an open 3/4 inch pipe it took about 11 to 12 minutes to get warm. At the most it seems like I can get the steam to the end of the main 3 to 4 minutes faster with maximum venting. Does that make sense it would still take that long (11 minutes) with an open pipe?

fud215

just a sugestion

you may have wrong size nozzel or partically blocked nozzel. i have had service calls were that was the problem.(in buildings and bakery ovens)   

Jeremy_16

About the Nozzle

That's a good thought. A few weeks ago the heating company came by and replaced the nozzle. It was undersized before and seemed to be set up incorrectly. The observation glass was all sooty before too. Now it is crystal clear and has been for a few weeks. I have a heating company coming back to take a look at the system and install a new low pressure gauge. We have a Weil McLain Model 80 Boiler with 8 sections. I think they wrote on the card that the new nozzle size is 4.25 (the old one was 3.75). I really have no idea what nozzle size is correct. I'm relying on them to tell me what's right.

nicholas bonham-carter

nozzle size

the W-M website should give the info on nozzle sizes for various sizes of their boilers.--nbc

Charlie from wmass

the load is important here for nozzle size

The old nozzle may have been put in to fire the boiler to match the load. In increasing the nozzle the boiler may now be over fired for the system. Was the system working before the nozzle was " improved" ?

Jeremy_16

The system:

The system produced heat, but not well to the top floor front units. The heating technician likened the smaller nozzle to "trying to boil water with a candle" or something like that. It's still not perfect; we still have days where the temperature of the top floor front units drops lower than the rest of the building, but it seems to have been better. It could also be that one of the service technicians who was here before changed the nozzle and it was wrong. The observation glass was all sooty so something was wrong with the way the burner was firing. I don't know if it was the nozzle size, but the head of the service department who just installed a bigger nozzle said we needed it.



What would happen if the system were overfired? How can I check?



I still need to add a few more Gorton #2's to the front of the building, as everyone has suggested. I went to pick a couple up at a local supply house, but the 2 they had in stock did not pass the blow test. I'm waiting for the next shipment.

jpf321

how badly did they fail?

how badly did they fail the blow test .. i'm pretty sure that humans can blow at relatively high pressure .. much higher than 1.5psi



i have a gorton that fails blowtest but very slightly .. that is when i blow really hard, the air seeps out .. but since i operate at 5oz .. it works just fine.



there was a post on here a while back about how hard someone can blow .. i'll have to try to find it.

Charlie from wmass

Over sized or "right" sized nozzle

A larger nozzle may waste fuel and cause short cycling of the boiler. The soot can be cause by many things including burred shoulder on the nozzle and a burner that was never tuned. Also leaking ropes on the combustion chamber can cause lots of extra air which can affect flame shape. Often times over sized oil boilers are down fired to better match the actual load of the building. A survey of the system as a complete unit needs to be done to accurately tell what the system needs for steam. I just installed 5 Gorton #2's on a system and they all work well. Can vents be added before the radiators to get the risers (stacks) filled faster?



added after rereading post

I guess you are adding vents, go away for a few days and the whole train goes past. Do you have an EDR for the building?

Jeremy_16

Blow Test

No air at all came out when I blew into the pair of Gorton #2s. I had bought 4 good ones the week before and could blow through them as easily as an open pipe so I figured something was wrong with the pair I was about to buy and said I would come back when they got a new shipment.

Jeremy_16

Charlie

So the only way to know the correctly sized nozzle is to see how many radiators (and which type etc) and piping are connected to the system? The last time the heating company came by, the tech only spent some time in the boiler room before telling us the boiler was underfired and that adding a bigger nozzle would help. He didn't go into each apartment and see what was connected. Does that mean he probably made a guess or is there another way to know what size to add? If he just upped the size without good reason it would use more oil for no reason then, right?



Even after he changed the nozzle, we are still having an issue with the top front apts. I  already added 2 Gorton #2's in addition to the already present Hoffman #75 on each long main running to the front. I know it is still recommended that I add more vents, and I plan on doing that, but is there anything else that could be going on here?



We added "master vents" at the top of the furthest from the boiler riser right before the radiator in each top floor front apt. Check out the last picture of the first post in this thread to see what we did. That's a Hoffman #75 in the picture.



As always, any comments and advice are appreciated. Thanks.

Charlie from wmass

I am thinking someone chose that nozzle for a reason

the reason could have been wrong but they had a reason. The load is one factor for nozzle size but the boiler and burner need to be kept with in certain parameters too. Jeremy can you do a radiator survey? Dans book E.D.R. will be able to give you the square footage of your radiators and then you add them up to check the boiler rating compared to the load. Often times symptoms are confused for causes with steam systems, actually with any heating system. Its like taking Advil for your sore shoulder and ignoring the fact you carry a 50 pound back pack off that shoulder for 10 hours a day. Some how that steam needs to get to the top and the rest of your building when you need it. It may be it never did well from day one due to poor layout of the piping. It may also be the other side is better insulated than it had been and this side is still not so the heat load has changed. A building may have be3en torn down or built near by that change the micro climate around your building from the day it was built. The question is simply how do we make what we have work.



The first step is to find out the connected load.

Jeremy_16

I think that the top floor front

was always harder to heat since my family acquired the building. Like you said, that doesn't mean it never heated well at some point though... I actually just ordered that book a couple of days ago. I will probably take me awhile to figure out the E.D.R because there are probably around 30 to 40 radiators in the building. Will that book show me everything I need to know?

Mike Kusiak_2

Appropriate nozzle and firing rate

A simple way to check if the firing rate is in the ballpark is to check and see if the burner cycles on the vaporstat or the thermostat (or heat-timer). If during normal operation the vaporstat cycles constantly during a call for heat, then most likely the firing rate is too high for the installed EDR. On the other hand, if during a recovery from setback the burner fires constantly for a long period and never cycles the vaporstat at all, chances are that the nozzle is too small and you are underfired.

By spending a little time observing the vaporstat while the burner is in operation you can get a pretty good idea of how well the firing rate is matched to the installed EDR.



Edit: I just read your more recent post where you mentioned that the tech now set up the system with HI-Lo-Hi modulation. The above only applies to on-off control of the burner, not the new modulation setup.



 In the case of Hi-Lo-Hi modulation, you would ideally have the boiler fire at Hi until all radiators were hot and filled with steam. At this point you would start to build pressure, and the vaporstat would switch the burner over to low fire where it would remain, maintaining constant pressure for the rest of the heat-timer cycle. If this is what is happening, then your firing rates are set up just about right.



Was the nozzle changed before or after the modulation was set up?

Jeremy_16

Mike:

Thanks for the reply. Yeah, this thread is getting long, so it's easy to miss something. The nozzle was changed the same day the modulation was set up.



When the burner first turns on it goes into high fire to start. It stays there for either a few minutes after start up (haven't timed exactly how long). It then proceeds to go into low fire for a couple of minutes then back to high fire for about 15 to 30 seconds and

then back to low fire for a few minutes. It keeps doing this until the call for heat is over.



The operating pressuretrol is currently set to cut-in at .5 psi and cut-out at 1.5 psi. The vaporstat that controls the low-high-low modulation is set to 14 oz with a 1 oz differential (the differential is subtractive). I also posted about this set-up in the control section:



[url=http://www.heatinghelp.com/forum-thread/129384/Carlin-Burner-Question-about-Low-High-Low]http://www.heatinghelp.com/forum-thread/129384/Carlin-Burner-Question-about-Low-High-Low



The last comment I got was from Steamhead. He suggested having my tech rework the firing rates so the low fire is higher and leave the high fire the same. I am still a little confused on exactly how the vaporstat is controling the fire while the pressuretrol is controling things too. Can anyone break that down for me? Are my vaporstat settings correct?

Mike Kusiak_2

Firing rate modulation

What Steamhead said is correct. Your Lo firing rate is just a little low and is inadequate to maintain the 14 oz pressure setting required by the vaporstat. In low fire, the pressure starts to drop and when it hits the threshold of setting minus differential, the vaporstat returns the burner to Hi fire until it reaches 14 oz again and the cycle repeats. In your present setup, the pressuretrol does nothing unless the pressure should rise to over 1.5 psi, so for all practical purposes it is now there just for a backup if the pressure should rise that high in low fire mode.

Your vaporstat differential seems a little low at 1 oz, which may be contributing to the Hi-Lo cycling. You might try increasing it to 2 or 3 oz, which should reduce the cycling. Another thing you can try is to reduce the vaporstat setting to 12 oz, which would not require as much of a Lo firing rate to maintain the lower pressure. You seem very close to the ideal settings, so just a little tweaking may possibly do the trick.

Jeremy_16

Fire Rate Modulation

Now I'm starting to understand how this works. Thanks for the explanation, Mike.



So the purpose of the operating pressuretrol is only to serve as a back up in the case that the low fire exceeds 1.5 PSI? We also have another backup pressuretrol with only a main scale (no differential scale) that serves as a back up.



To make sure I understand. The burner starts up in hi fire and stays there until the cut-out (14 oz on my system) when it then kicks into low fire. If the pressure drops one ounce (the differential on my system) the hi fire kicks back in until it reaches 14 oz again. Is that right? Is the goal to maintain 14 oz of pressure so the burner doesn't return to high fire during the same call for heat?



I think I understand now what Steamhead suggested. It seems like there are 3 ways to solve the cycling issue then:

1. increase firing rate of low fire mode (I have no idea how to do that, but that's what the tech could do)

or 2. lower cut-out setting on vaporstat

or 3. increase differential of vaporstat



Is that right? If so, is one of the solutions better than the next?

Mike Kusiak_2

Understanding how it works

Yes, I think you now pretty much understand how it works. You want to start the call for heat at high fire, to rapidly exhaust the air from the system and fill the piping and radiators with steam. Once the vents close and the radiators are hot, the system will start to build pressure. Now you need a lower firing rate (less heat) to prevent the pressure from continuing to increase. This is what your vaporstat is now doing, sensing when the pressure reaches 14 oz and activating low fire which ideally would maintain the 14 oz until the call for heat ends. Your Lo firing rate is slightly less than what is needed to maintain the constant pressure, so as it drops to 13 oz, the vaporstat again activates Hi fire to bring up the pressure to 14 oz again. Because your differential is so low, only an ounce of pressure change is causing the switching. If you increased the differential it would require a greater drop in pressure to activate high fire and therefore the cycling would definitely occur less often, although it might not completely eliminate it.





Increasing the differential is a very simple adjustment, so it is what I would try first. Reducing the 14 oz setting is also simple and easy to try. Steamhead's solution is really the best, but the firing rate adjustment must be be done by a trained tech with the right equipment, so I would save that for last.





Right now, your operating pressuretrol does nothing, because in low fire the system cannot even maintain constant pressure, so it will never reach the 1.5 psi cutout. If however your Lo fire setting was too high, the pressure might gradually increase until it reached the cutout setting, thereby shutting of the burner an preventing the pressure from rising higher.

Jeremy_16

UPDATE

Firing Rates

I finally got the service tech back to try to clear things up. He told me that there is only one nozzle and the firing rate for the low and high fire is changed by pump pressure. He said that the low fire is 4.25 GPM and the pump runs at 100 pounds pressure and the high fire is around 6.5 GPM and the pump runs 300 pounds of pressure. (hopefully I got all the terms right)



The tech put the vaporstat up to 16 oz. The boiler now stays in high fire for longer than a normal length call for heat. I put it in bypass and it took 27 minutes for the burner to go into low fire. It then only stayed in low fire for 20 to 30 seconds before going back to high fire for a minute. It kept repeating this until I shut the burner. The tech said that we need to be able to have 1 pound of pressure in the radiators upstairs and if we don't have it in the boiler room then we don't have it upstairs. (Even though the pressure didn't reach 1 pound for a long time, the radiators on the top floor still got hot all the way across). I'm not sure what to think here. Question 1: Does that matter that we don't have 1 pound of pressure upstairs????



EDR: I looked at all of the steam radiators and couldn't find the exact kind in Dan's book. Most of the radiators I believe say "Gurney" as the type or maker. It's really hard to read. Anyway, I measured a few of them and since they were the same in many units, I approximated about how many square feet we have total. The steam heat is only on floors 2, 3 and 4. In those floors the total radiators add up to 1200 square feet EDR. I think I read that if you have mains that are not insulated (mine are not all insulated) you should use a larger pick up factor of 1.5 instead of 1.33, but I'd like to know what any of you suggest. Question 2: If we use 1.5 then we have 1800 total EDR, right? The first floor forced hot water radiators and baseboard are not included in the radiator EDR calculation above. I wasn't quite sure how to add that in. Question 3: Does this help in determining the nozzle size? Can someone give me advice on if our sizes are close to what they should be?



Connected Mains. We have 5 mains in the building: 2 long ones to the front with some small branches and 3 shorter ones to the back.



All mains (front and back) share 11ft of 4 inch pipe that rises from the header.



Front Main #1 then goes 70 ft. with 3 inch pipe.

Front Main #2 goes 65 ft. with 3 inch pipe.



The back mains share 7 ft run of 3 inch pipe and then split 3 ways:



Back Main #1 30 ft. of 2.5 inch pipe

Back Main #2 20 ft of 2 inch pipe

Back Main #3 36 ft of 2 inch pipe



Questions 4: When figuring out venting at one ounce of pressure can I divide the air in the first 11 feet of shared 4 inch pipe by 5 (there are 5 mains total) because that way vents in the front and back can share the venting load. Same question with the shared 7 feet of 3 inch pipe to the back of building. Can I divide that by 3 so the back 3 mains share the venting load?



Update about Problem

When I started this thread we could not get the top floor front apartments to heat as well as the rest of the building. This may be a venting issue or the way we set up the heat timer control, or something else. Two days ago the only thing I changed was adding venting to the back 3 mains. I put in one hoffman 75 on back main #1, one Gorton #1 on back main #2, and 1 hoffman 75 on back main #3. Front main #1 already had 3 Gorton #2s and Front Main #2 also had 3 Gorton #2s. I figured that since the back was always warmer than the front, I wouldn't need as much venting. The only reason I added any main vents to the back was because the second floor was getting very hot and I thought adding main vents would help balance the heat across the floors in the back.



As soon as I added main vents to the back, the front apartments (2nd, 3rd, and 4th floors) all got warmer over the next day (around 72 to 74 degrees) and the rear apartments stayed cooler (the rear 2nd and 3rd floor were 67 and 68 degrees and the fourth floor rear apartments were 62 and 64 degrees). It was almost as if my problem switched from the front to the back. I can't figure out what is going on. The only difference that occurred at the same time is that it has been cloudy the past two days as well and the back apartments usually get sun for the whole day. Question 5: Should I add more venting to the back?



Sorry for such a long post, but there was so much information to convey. Any advice people can give is very much appreciated. I hope I can figure this out.

nicholas bonham-carter

some apartments chilly..some not

this system would be an ideal one to survey with an I.R. camera. with the boiler firing from fairly cold, start in the basement, and see how the mains heat up, especially the risers. use a jumper on the boiler to fire it continuously for the test. repeat the test for the top floor to see where steam arrives first. you may need larger radiator vents on the top floor, with regular hoffmans on the 2nd, and 3rd.

in the absence of a camera, the ouch test with hands on the pipes works well enough. don't concern yourself with apartment air temperature, until you have all rads getting steam almost simultaneously.

on my 3-storey, 1-pipe system, with 55 radiators, and 1,050,000 BTU, i have 6 returns coming back to the boiler, with 3 gorton#2's, plus 1 hoffman 75 on each. the antlers are quite long so there is less likelihood of premature vent closing. since you have a vaporstat, i would reduce the pressure to 8 oz, and see if that makes any difference. steam travels more quickly at low pressures. in the spring and fall with short boiler firings, you need all the air out as quickly as possible. don't forget that the steam chest of the boiler also has air to be removed, so increase that venting. the goal is to have the supply pipes, and returns filled with steam as quickly as possible.--nbc

Jeremy_16

Nicholas:

Thanks for the response. When I put the boiler in bypass it runs continuously. That should be the same as what you are saying about putting a jumper on right?



Two other people and I ran around the building timing how long it took the risers to get warm about two weeks ago. At this point in time we had gorton #2s on the front mains and no main vents on the back. We checked the third floor risers because the risers go right into the radiator on the fourth floor and aren't visible. During the test the front risers heated up at about the same time as the riser coming up from the shortest main in the back (8 to 9 minutes or so). The risers coming up from the two longer mains in the back actually took a lot longer to heat up (which isn't surprising because they had no main vents below).



Somehow though, the rear apartments were still warmer (72 to 74 degrees) and the top floor front apartments were colder (60-62 degrees). All radiators could and do get hot all the way if the boiler runs long enough. That's when I thought the control was preventing the burner from turning on because the warmer apartments factored into the space average and wouldn't allow the burner to come back on. If the building was perfectly balanced, but the apartments in the back got a lot of sun, they would heat up more and the space average would rise, telling the burner not to turn on. I took all of the warmest apartments in the back out of the equation about a week ago.



I then added main vents to the rear and the situation appears to be reversed as stated above. I guess I should run around and see how long it takes the risers to get warm again. It's been cloudy and stormy the past few days so the back apartments aren't warming at all with the sunlight that normally hits them (that could probably add 4 or 5 degrees). It's weird that only the top floor in the back gets temperatures as low as 60 and 64 while the front is now up to 74.



I can lower the pressure on the high/low vaporstat from 16 oz to 8 oz, but then I wouldn't be able to get a pound of pressure at the top floor radiators like the service tech said I needed... Any idea why the service tech told me that I need a pound of pressure up at top floor radiators? Is that not true? He seemed to think that I needed to have up to a 1.5 PSI at the boiler otherwise I would have "lazy steam". From reading Dan's books and looking at the forum I know that everyone always says lower the pressure and that vaporstats are great to have and if you have the proper venting you can run on lower pressure. Can my 4 story building run well off of the vaporstat? When I asked the tech why we need higher pressure he said, "that's not high pressure, high pressure is 5 or 6 pounds. You need 1.5 pounds for this building." Is that just wrong? Is there any reason we would need more pressure than a vaporstat control can supply? I'm definitely willing to try lowering the pressure, but I'm just trying to figure if what the tech is telling me is wrong or if not, why could be right.

nicholas bonham-carter

wrong?

yes, less pressure is the new more with steam. a couple of ounces is enough. the point i was trying to make was to follow the steam as it rises from the basement mains, and then track it as it rises from the basement to the top floor. you may have a little obstruction, and never find it unless you follow the steam. the I.R. camera would make the task easier! ggod luck!--nbc

Mike Kusiak_2

Get a new tech

Looks like you need to get a more knowledgeable tech. Simply increasing the pressure is not going to resolve what appears to be a venting problem. You mentioned that all the top floor radiators were hot all the way across long before the pressure reached 1PSI. If that is true then you really don't need anywhere near 1 PSI to fill the system completely with steam. As Nicholas suggested, I would try gradually reducing the vaporstat cutout setting from the present 16 oz and see how the system responds.

nicholas bonham-carter

another thought

the heattimer system will only work effectively, and comfortably, when the system is perfectly balanced/vented. why not just use a good steam-rated thermostat until you have worked these problems out. i would suggest a honeywell visionpro with a remote sensor located in the apartment with the most winter exposure [north east?]. if because of it's exposure, you find it too sensitive, then you can set the temperature down to 67 deg.

and yes, you need a new tech who knows something about steam. as you may have read here, the empire state building needs 1.5 psi, but not your building! was he the reason for the heattimer?--nbc

Jeremy_16

Less Pressure & Venting Question

Thanks for the responses, Nicholas and Mike. I'll try lowering the pressure and see what happens. The system will probably stay in high fire for a shorter period of time, and low fire may be able to maintain longer. Do I want the system to stay in high fire until heat circulation is established (eg. stay in high fire until steam reaches last radiator in system and then go to low fire)? What signs should I look for to know when the pressure is at the right setting?



As far as venting: if 3 mains share 11 feet of 4 inch pipe before splitting up, can I divide the amount of air in the shared part of the main by 3 so each of the vents at the end of the 3 mains help vent the air out? This seems pretty intuitive, but I figured I should make sure before spending the money on vents. The total cubic feet of air in that shared part of the main would be .99 cubic feet. If each main needs to vent the air on its own I would need 1 Gorton #2 (1.1 cfm each) on each of the mains in the back to vent the air at one ounce of pressure. If they all contribute to the venting I would only need 1 Gorton#1 (.33 cfm each and much cheaper $$) on each back main.



Thanks

Jeremy_16

Heat-Timer Control

No, he wasn't the reason for the heat-timer. We had an old

heat-timer before and I guess we just decided to go with the new one because we

met with one of the sales reps who said we would lower our oil consumption a

lot with the new MPC platinum.



I don't have the numbers on me now, but I think we lowered our consumption

around 15% with the new heat-timer. That's before we started adding the venting

over the last month and tweaking the system more. I can take the space lock

feature off or change which apartments are factored into the space lock. Going

forward I plan on lowering the pressure as suggested, adding more venting to

the back, taking the back apartments with sun exposure out of the heat-timer

space lock equation (that way if the building is balanced, but the rear

apartments with sun heat up more, it can't throw the heat-timer off with high

averages causing the burner to not run)



What are the advantages of the Honeywell visionpro and how does it work

differently? How much is it?

Mike Kusiak_2

Less pressure

Yes, ideally you would want the boiler at high fire until all the radiators were hot and filled with steam. Until that happens, the system will not be able to increase pressure because the vents are still open and all the steam is condensing as fast as it can be produced. Once the vents close and the radiators are at steam temperature, steam cannot condense as fast as it is being made,  which causes the pressure to start to rise. At this point you want the boiler to go to low fire so the steam production is just adequate to meet the ability of the radiators to condense it. Now the system is in equilibrium at low fire and should operate at constant pressure until the call for heat ends.





I would continue to lower the vaporstat setting until the system remains in low fire without excessive cycling until the call for heat ends. If you reduce the setting too much,  the burner will go to low fire before the furthest radiators are completely hot and the heating will become less even. You really want a setting in between that point and where you are now.





The Heat-timer you have is more suitable for your application than the Vision-Pro because it allows for multi-indoor sensors and also takes into account outdoor temperature when calculating the heating cycles. Getting it to work correctly is more a matter of determining which apartments should be sensed to provide the most accurate overall control of the building